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2 Sheets-Sheet 1.

D. MEASTON. METHOD 0F TANNING.

Patented May 31, 1898.

INVENTDR 2 Sheets-Sheet. 2. EASTON.v

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DOUGLAS M. EASTON, OF WEYMOUTII,MASSACHUSETTS, AssIGNOR To MARSHALL C. DIZER, SILAS C. SAME PLACE.

METHOD O DIZER, AND VALTER M. DIZER, OF

F TANNING.

SPECIFICATION forming part of Letters PatentgNo. 604,739,dated May 31, 1898.

Application filed November 30, 1897,

To all whom t may concern.-

Beit known that I, DOUGLAS M. EASTON, a citizen of the United States residing at East W'eymouth, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements` in Methods of Tanning Hides; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

'lhe present invention relates to the manufacture of leather, and 'more particularly to an improved method of tanning hides.

Inthe art of tanning as heretofore practiced 1t has been customary to place the hides in a rotating or reciprocating vat and to impart to said vat a Violent and rapid motion to cause the tanning liquor to be forced into the pores of the skin in order to expedite the tanning process; but such tumbling or shaking of the hides is very objectionable for the reason that the leather produced is apt to have a round hard grain, and, furthermore; the skins are often damaged by the' rough usage to which they are subjected.

To overcome the objectionable features of the process above referred to, ithas been proposed to suspend the hides in -a stationary air and fluid tight vat and to force tanning liquors of different strength into said vat under hydrostatic pressure to act upon the hides therein, (see, for example, patent to Warrand,

No. l517,083., dated March 27, 1894;) but the apparatus necessary to carry out such process is expensive and complicated, and by reason of the successive introduction into the vat of'tanningliquors of different strength the results secured, unless the greatest care be used, are not uniform. It will be also noted that in processes similar to the Warrand process above referred to not only does the strength ofthe liquor vary as successive sets of tanks are brought into operation, but also while the same set of cooperating tanks upon thesamelevel are beingused thestrength of the tanning liquor which is circulated throughthe vatis being constantly dimin- -ishedas the hides boing acted upon take up the tanningsu'bstanees from said liquor. The

Serial No. 660,191. (No specimens.)

hides are therefore at each step being treated by a tanning liquor constantly losing in strength, a' feature which tends to retard the tanning operation and clearly distinguishes a process of this nature from the present process, as hereinafter described.

Another process which has been proposed in the'prior art is to suspend the hides in a stationary vat which is filled with liquor from a leaching-vat, a junk-vat being provided to receive the.liquor from the tanning-vats, which is afterward pumped backinto the leaching-vats for the purpose of renewing its strength; but in such process the flow of liquor is not continuous and the -liquor is not kept at a constant temperature or uniform strength, so that the best results are :not sccured.

AThe object of the present invention is to provide an improved process of tanning requiring no special skill or attention in its practice to secure uniform results and Whereby the time required to complete the operation of tanning will be greatly reduced, and the tanned leather Will be free from the round able, and heavier for a given weight of hide proposed.

To the above end the' present invention consists-of the process which will be hereinafter set forth and claimed.

In the aceompanyingdrawings isi ll ustrated a preferred form of vthe improved apparatus for carrying out the present invention, in whichj Figure 1 shows a plan View thereof. Fig. 2 shovvs a longitudinal section through the Well and one row of vats, as seen in Fig.' 1, parts of the device being in elevation. Fig. 3 shows a transverse section through opposite vats. Fig. 4 is a detail view representing the arrangement of the vats and the means for 'regulating the height of the liquor therein.

the Well, showing the arrangement of the steam-(foils therein.

Similar letters of reference represent correspending parts throughout the several `views. In the drawings, A represents the Well in than that producedby processes heretofore` Fig. 5 is a transverse sectional view through 9 ICO - which the tanning liquor is placed, and A' 2 Uvex, :ou

represents a vat or a series of vats in which the hides are placed, said vats comprising any suitable number and lbeing preferably of the shape and arrangement shown in the drawings.

In the present method the hides are lield in the vats A free from motion, withthe exception of such motion as may be imparted thereto by the flowing tanning liquor, and are subjected to a continuous iiow of tanning liquor, which is maintained at an even tcmperature and at a constant specific gravity, whereby a very rapid and uniform action is secured on the hides without forming the round hard grain onthe .leather before referred to.

In the apparatus of the drawings the liquor containing the proper tanning ingredients for the particular hides being tanned is placed in the well A, in which it is heated. The

heated liquor is conducted from said well to and through the vats A and from the vats back to the well A, the influent stream of liquor entering each vat being substantially equal to the ellluent stream which is leaving the same, so that while being constantly changed the liquor in the several vats in which the hides are submerged stands at a constant level and has no movement except the circulation caused by the influent and efliuent streams. f p

The well A isflocated at one end of the series of vats A', and, as shown in Figs. 2 and 5, the bottom of the well A is somewhat lower than the bottom of the vats A' in order that the liquor in the vats may jiow by gravity back'to the well after it haspassed through the vats and actedupon the hides therein. The well A may be of any suitable construction, that shown in the drawings being a rectangular box having side walls d and end walls a'. In thewell A, and preferably near the bottom thereof, is a steam-coila?, through which steam is constantly forced from any suitable source to heat the tanning liquor.

. The tanning liquor is pumped up from the well A by means of a suitable pump B, which raises the liquor through a pipe b, extending into the well A, and discharges the liquor into a conduit or trough b', which is inclined from said pump toward the vats A', as clearly shown, and from which it Hows 'into the vats,

said trough being closed at its end and having along its sides openings b2, from which A the liquor flows to the vats A'.

In the drawings are shown six vats arranged 1n parallel rows of three, and for convenience the trough b is located between the rows and has openings b2 through bothof its walls but it is to be clearly understood that the arrangement depicted in the drawings is merely illustrative of a preferred form of the apparatus and that the present invention is not limited to any particular arrangement or number of vats, it being simply necessary to so arrange the well and vats and the connecting conduit or trough that a constant circulation of the tanning liquor from the well to the vats and from the vats back to the well will be produced sufficiently rapid to prevent atoo great cooling of the liquor in the vats.

From the side or end of each vat A' leads a discharge-pipe C, which extends to and empties into a trough c, which is conveniently arranged along one side of the'row of vats, as shownvin Fig. 1, and which trough is inclined downwardly toward the well A and communicates with said well by an opening or.3 in one end thereof, as clearly shown in Fig. 2..

As shown in the drawings, the dischargev pipes C communicate with the respective vats A' near the bottom, and their outer endsc are arranged to project upwardly toward the top'of the vats A', and the open ends of said pipes are disposed directly over the trough c, so that the tanning liquor discharged therefrom will4 fall into said trough and be conv eyed back to the well A.

In practice the ends c' of the dischargepipes C are preferably so arranged that they may be inclined more or less, as desired, in order to control the height of tanning liquor contained in the vats. It is important to note in this connection that the heated liquor is discharged directly from the conduit or trough b' into each of the seriesof vats A and does not iiow from vat to vat. This feature is of importance where my improved process is carried out by an apparatus comprising more than one vat, since if the liquor were discharged into one vat from the conduit or trough and allowed to flow into the succeeding vats the temperature of the liquor in the several vats would vary. A

The vats A' are provided with any suitable means to suspend thehides therein, in the apparatus ofthe drawings such means consisting of suitable projecting. ribs a, which of the tanning substances from theliquor by' the hides during the tanning operation, tanning liquor of the required strength is added to the liquor in thewell A as required to keep the liquor in the vvats at a uniform strength. While such liquor may be added by any suitable means without departing from the spirit of the present invention, I prefer that the same should be allowed to run into the tank A in a constant stream of suicient volume.

In' practice I have found it desirable to use for tanning steer-hides liquorof 'a strength of from 9 to 10 Baume and forcalf-skins from"5 to 6 Baum,xand to supply the tanning substances as absorbed by the hides I allow a small stream to owinto the tank A from a barrel N or other suitable receptacle IIO containing the usual commercial extract, which will average about Baume. Where such extract is used, to secure a product of about fty hides a day I iind that about three barrels a day added extract gives the best re-` sults. For calf-skins requiring weaker liquor less extract is added. If the liquor becomesv A too strong, the extract may be reduced or water added to the liquor in the tank A.

It will be noted that the constant supplying of new liquors as required to keep the liquors in the vats at a constant strength will cause a continued increase in the total amount of liquors in the system and that some provision is necessary to prevent such accumulation of liquors or to properly dispose of the surplus. Eer the above reason I have found it preferable to provide open vats or-vats so constructed that the liquors therein are exposed to the action of the atmosphere, by which arrangement I nd in practice that the evaporation of the liquors will prevent the accumulation above referred to and maintain a practically constant quantity of liquor in the system. I may further sayin this connection that to facilitate the evaporation of the liquors, as above described, I find it desirable in practice to keep the liquors in the vats at a temperature a little above that of the atmosphere.v I may further sa .y that the constant removal of old liquors byevaporation, as above described, and the constant supplying of new liquors to replace the same tends to keep the liquors sweet and pure and greatly facilitates the tanning operation.

While, as before stated, the evaporation of the liquor as above described is of considerable importance and materially contributes to the successful results secured by my improved process, I do not consider such feature as absolutely essential to the successful operation of my process, although it possesses marked advantages over any other means known to me for preventing the accumulation of liquors. I would also say that I do not desire to limit my present invention to the specific means employed to keep the liquors at a constant strength, it being only essential that the :required quantity of liquor shall be preserved to flood the hides and that the tanning substances taken up from the liquor by the hides shall be restored to keep the liquor at a substantially uniform specific gravity or strength throughout the tanning process.

In carrying out my improved process by the apparatus of the drawings the Well A is filled with tanning liquor of the lrequired strength, which is lbrought to the proper heat (preferably from 75o to 80 Fahrenheit) by means of the steam-coil ce2. The liquor is then pumped out of the tank A into the conduit or trough b and iiows into the vats A', the liquor in the well A being replenished as required until all the vats are lled with heated liquor, and this operation is continued until the liquor in all the vats has reached the required temperature, (preferably to Fahrenheit,) which is substantially uniform throughout all the vats. The hides, which have been previously nailed or otherwise suitably secured to the bars a5, are then immersed in the liquor, the bars a5 resting upon the ribs a4, so that the hides are suspended out of contact, but close together, for economy of space.

The length of time which the hides are allowed to remain in the vats depends upon the nature of the hide, an average steer-hide requiring about ten days, while a calf-skin ma be tanned in twenty-four hours. Y While the hides remain in the vats the pump is kept constantly in operation and the.

a constant inflow from the tank to the vats and an` outiiow from the vats to the tank. The tank A in my improved apparatus may 'be aptly termed a rectifying-tank, for in the passage through the same from the vats the liquors are supplied with their lost heat and strength, so that the changing liquor in the vats is kept at a substantially uniform temperature and specific gravity.

While I have defs1 bed my improved proccss and the preferred form of my apparatus whereby the same may be practiced, it is to be understood that the practice of myv process is not dependent upon the particular apparatus described, but may be practiced by any desired apparatus. I do not claim the apparatus herein, but in a copending divisional application, Serial No. 67 7 ,584, filed April 14, 1898; butv What I do herein claim as novel, and desire to secure by Letters Patent of the United States, is

l. An improved'method of tanning consisting in iiooding the hides in a stationary vat with a continuously-owing tanning liquor kept at a substantially uniform temperature and strength, substantially as described.

2. An improved method of tanning consist-l ing of flooding the hides in a stationary vat with a continuously-flowing tanning liquor exposed to the action of the atmosphere and kept at a substantially uniform temperature and strength.

In testimony whereof I affix my signature in presence of two Witnesses.

DOUGLAS lli. EASTION.

Witnesses:

CHARLES B. CUsHING, WM. M. REAMY.

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